Airline quick disconnects are made by several manufacturers and it’s not always clear if they are compatible. The ones that come installed on the California Air Tools CAT-10020C air compressor have an outer ring design that’s different from perhaps more standard Milton quick disconnects. The CAT quick disconnects may be more susceptible to damage. This video is of replacing a damaged quick disconnect. The leak was actually louder than the compressor while running.
Even with the replaced quick disconnect, the slightly pressure on the side of a connected air line causes a leak. This may be because Milton plugs are not completely compatible. It’s worth considering replacing both disconnects on the CAT air compressor with ones of the preferred manufacturer. Then there would be no doubt of compatibility.
The video quality is lower than normal because I had to crop a lot from the recording.